Add CCACHE_EXTRAFILES feature

NEWS.txt

@@ -65,6 +65,9 @@ New features and improvements
       hash anything), mtime (hash the compiler's mtime and size) and content
       (hash the content of the compiler binary). The default is mtime.
 
+    - It is now possible to specify extra files whose contents should be
+      included in the hash sum by setting the `CCACHE_EXTRAFILES` option.
+
     - Temporary files are now created in the directory they will end up in.
       This makes ccache more friendly to Linux's directory layout.
 

ccache.c

@@ -761,6 +761,7 @@ static void calculate_common_hash(ARGS *args, struct mdfour *hash)
 {
 	struct stat st;
 	const char *compilercheck;
+	char *p;
 
 	hash_string(hash, HASH_PREFIX);
 	hash_delimiter(hash);
@@ -820,6 +821,23 @@ static void calculate_common_hash(ARGS *args, struct mdfour *hash)
 		}
 	}
 	hash_delimiter(hash);
+
+	p = getenv("CCACHE_EXTRAFILES");
+	if (p) {
+		char *path, *q;
+		p = x_strdup(p);
+		q = p;
+		while ((path = strtok(q, " \t\r\n"))) {
+			cc_log("Hashing extra file %s", path);
+			if (!hash_file(hash, path)) {
+				stats_update(STATS_BADEXTRAFILE);
+				failed();
+			}
+			hash_delimiter(hash);
+			q = NULL;
+		}
+		free(p);
+	}
 }
 
 /*

ccache.h

@@ -49,6 +49,7 @@ enum stats {
 	STATS_CACHEHIT_DIR,
 	STATS_NOOUTPUT,
 	STATS_EMPTYOUTPUT,
+	STATS_BADEXTRAFILE,
 
 	STATS_END
 };

manual.txt

@@ -213,6 +213,12 @@ cases you won't need any of these as the defaults will be fine.
     *CCACHE_EXTENSION* option to override the default. On HP-UX set this
     environment variable to *i* if you use the ``aCC'' compiler.
 
+*CCACHE_EXTRAFILES*::
+
+    If you set the environment variable *CCACHE_EXTRAFILES* to a
+    space-separated list of paths then ccache will include the contents of
+    those files when calculating the hash sum.
+
 *CCACHE_HARDLINK*::
 
     If you set the environment variable *CCACHE_HARDLINK* then ccache will

stats.c

@@ -72,6 +72,7 @@ static struct {
 	{ STATS_OUTSTDOUT,    "output to stdout               ", NULL, 0 },
 	{ STATS_DEVICE,       "output to a non-regular file   ", NULL, 0 },
 	{ STATS_NOINPUT,      "no input file                  ", NULL, 0 },
+	{ STATS_BADEXTRAFILE, "error hashing extra file       ", NULL, 0 },
 	{ STATS_NUMFILES,     "files in cache                 ", NULL, FLAG_NOZERO|FLAG_ALWAYS },
 	{ STATS_TOTALSIZE,    "cache size                     ", display_size , FLAG_NOZERO|FLAG_ALWAYS },
 	{ STATS_MAXFILES,     "max files                      ", NULL, FLAG_NOZERO },

test.sh

@@ -41,6 +41,7 @@ unset CCACHE_CPP2
 unset CCACHE_DIR
 unset CCACHE_DISABLE
 unset CCACHE_EXTENSION
+unset CCACHE_EXTRAFILES
 unset CCACHE_HARDLINK
 unset CCACHE_HASHDIR
 unset CCACHE_LOGFILE
@@ -1095,6 +1096,56 @@ readonly_suite() {
     ##################################################################
 }
 
+extrafiles_suite() {
+    ##################################################################
+    # Create some code to compile.
+    cat <<EOF >test.c
+int test;
+EOF
+    echo a >a
+    echo b >b
+
+    ##################################################################
+    # Test the CCACHE_EXTRAFILES feature.
+
+    testname="cache hit"
+    $CCACHE $COMPILER -c test.c
+    checkstat 'cache hit (preprocessed)' 0
+    checkstat 'cache miss' 1
+
+    testname="cache miss"
+    $CCACHE $COMPILER -c test.c
+    checkstat 'cache hit (preprocessed)' 1
+    checkstat 'cache miss' 1
+
+    testname="cache miss a b"
+    CCACHE_EXTRAFILES="a b" $CCACHE $COMPILER -c test.c
+    checkstat 'cache hit (preprocessed)' 1
+    checkstat 'cache miss' 2
+
+    testname="cache hit a b"
+    CCACHE_EXTRAFILES="a b" $CCACHE $COMPILER -c test.c
+    checkstat 'cache hit (preprocessed)' 2
+    checkstat 'cache miss' 2
+
+    testname="cache miss a b2"
+    echo b2 >b
+    CCACHE_EXTRAFILES="a b" $CCACHE $COMPILER -c test.c
+    checkstat 'cache hit (preprocessed)' 2
+    checkstat 'cache miss' 3
+
+    testname="cache hit a b2"
+    CCACHE_EXTRAFILES="a b" $CCACHE $COMPILER -c test.c
+    checkstat 'cache hit (preprocessed)' 3
+    checkstat 'cache miss' 3
+
+    testname="cache miss doesntexist"
+    CCACHE_EXTRAFILES="doesntexist" $CCACHE $COMPILER -c test.c
+    checkstat 'cache hit (preprocessed)' 3
+    checkstat 'cache miss' 3
+    checkstat 'error hashing extra file' 1
+}
+
 ######################################################################
 # main program
 
@@ -1123,6 +1174,7 @@ direct
 basedir
 compression
 readonly
+extrafiles
 "
 
 if [ -z "$suites" ]; then